No abstract

BackgroundWheat (Triticum aestivum L.) is an economically important grain crop. Two-dimensional gel-based approaches are limited by the low identification rate of proteins and lack of accurate protein quantitation. The recently developed isobaric tag for relative and absolute quantitation (iTRAQ) method allows sensitive and accurate protein quantification. Here, we performed the first iTRAQ-based quantitative proteome and phosphorylated proteins analyses during wheat grain development.ResultsThe proteome profiles and phosphoprotein characterization of the metabolic proteins during grain development of the elite Chinese bread wheat cultivar Yanyou 361 were studied using the iTRAQ-based quantitative proteome approach, TiO2 microcolumns, and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Among 1,146 non-redundant proteins identified, 421 showed at least 2-fold differences in abundance, and they were identified as differentially expressed proteins (DEPs), including 256 upregulated and 165 downregulated proteins. Of the 421 DEPs, six protein expression patterns were identified, most of which were up, down, and up-down expression patterns. The 421 DEPs were classified into nine functional categories mainly involved in different metabolic processes and located in the membrane and cytoplasm. Hierarchical clustering analysis indicated that the DEPs involved in starch biosynthesis, storage proteins, and defense/stress-related proteins significantly accumulated at the late grain development stages, while those related to protein synthesis/assembly/degradation and photosynthesis showed an opposite expression model during grain development. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis of 12 representative genes encoding different metabolic proteins showed certain transcriptional and translational expression differences during grain development. Phosphorylated proteins analyses demonstrated that 23 DEPs such as AGPase, sucrose synthase, Hsp90, and serpins were phosphorylated in the developing grains and were mainly involved in starch biosynthesis and stress/defense.ConclusionsOur results revealed a complex quantitative proteome and phosphorylation profile during wheat grain development. Numerous DEPs are involved in grain starch and protein syntheses as well as adverse defense, which set an important basis for wheat yield and quality. Particularly, some key DEPs involved in starch biosynthesis and stress/defense were phosphorylated, suggesting their roles in wheat grain development.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-1029) contains supplementary material, which is available to authorized users.

The drought-tolerant ‘Ningchun 47’ (NC47) and drought-sensitive ‘Chinese Spring’ (CS) wheat (Triticum aestivum L.) cultivars were treated with different PEG6000 concentrations at the three-leaf stage. An analysis on the physiological and proteomic changes of wheat seedling in response to drought stress was performed. In total, 146 differentially accumulated protein (DAP) spots were separated and recognised using two-dimensional gel electrophoresis. In total, 101 DAP spots representing 77 unique proteins were identified by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. These proteins were allocated to 10 groups according to putative functions, which were mainly involved in carbon metabolism (23.4%), photosynthesis/respiration (22.1%) and stress/defence/detoxification (18.2%). Some drought stress-related proteins in NC47, such as enolase, 6-phosphogluconate dehydrogenase, Oxygen-evolving enhancer protein 2, fibrillin-like protein, 2-Cys peroxiredoxin BAS1 and 70-kDa heat shock protein, were more upregulated than those in CS. Multivariate principal components analysis revealed obvious differences between the control and treatments in both NC47 and CS, while cluster analysis showed that the DAPs displayed five and six accumulation patterns in NC47 and CS, respectively. Protein–protein interaction network analysis showed that some key DAPs, such as 2-Cys peroxiredoxin BAS1, RuBisCO large subunit-binding protein, 50S ribosomal protein L1, 6-phosphogluconate dehydrogenase, glyceraldehyde 3-phosphate dehydrogenase isoenzyme and 70-kDa heat shock protein, with upregulated accumulation in NC47, had complex interactions with other proteins related to amino acid metabolism, carbon metabolism, energy pathway, signal transduction, stress/defence/detoxification, protein folding and nucleotide metabolism. These proteins could play important roles in drought-stress tolerance and contribute to the relatively stronger drought tolerance of NC47.

No abstract

The embryo and endosperm of wheat have different physiological functions and large differences in protein level. In this study, we performed the first integrated proteome analysis of wheat embryo and endosperm in response to the water deficit during grain development. In total, 155 and 130 differentially expressed protein (DEP) spots in the embryo and endosperm, respectively, were identified by nonlinear two-dimensional electrophoresis and tandem mass spectrometry. These DEPs in the embryo were mainly involved in stress/defense responses such as heat shock-related proteins (HSP) and peroxidase, whereas those in endosperm were mainly related to starch and storage protein synthesis such as α-amylase inhibitor and the globulin-1 S allele. In particular, some storage proteins such as avenin-like proteins and high-molecular weight glutenin subunit Dy12 displayed higher expression levels in the mature endosperm under a water deficit, which might contribute to the improvement in the quality of breadmaking.